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Topic: will this motor work (Read 1054 times)

I obtained this motor from a cd-drive and i identified it as a brushless motor funny thing is that it has 2 contact points that one touched with a 9.v battery it spins happily it does not have 3 contacts as most brushless have.Question is am i mistaking it for a brushed motor because of its shape2)is it a good substitute for a 9v battery that can run in the $40 Robot by pratheek.MODEL NUMBER

If it has only 2 wires, it's a brushed motor (we are talking about DC motors only, some AC motors have 2 wires and they are brushless), which You proved by plugging it to 9V battery and seeing it spin. Brushless motors have more than 2 wires and would not spin when plugged directly to power source.

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"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

Say my robot has wheels of 2.5cm radius (0.025m), this tells us that motor should output at least T = 0.025m * 0.8896N = 0.02224N*m (Newton meters) of torque, but we don't want motor to run at 100%, so lets do this NewTorque = 0.02224N*m / 0.75 = 0.03N*m;

« Last Edit: March 06, 2013, 11:51:55 AM by newInRobotics »

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"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

The easiest way to increase torque is to use a rubber band across the output shaft of the motor (small diameter) and then across a large wheel/cup/plate/disc on your actual wheel shaft. Maybe even directly around the wheels. Getting the rubber band to stay on and not jump off is tricky; you may need to build some rims with glue or epoxy or plastic or something.

and BTW I would guess the top motor is the best. The ones at the bottom, as far as I know have very low torque.

Well thanks for the reply i do not have any gears(cant obtain them) and e-bay does not ship to my area.well i tried all the motors in the picture directly with a 9v and they did not show any burning signs so i guess they go well with 9v.The weight is around half KG

Say my robot has wheels of 2.5cm radius (0.025m), this tells us that motor should output at least T = 0.025m * 0.8896N = 0.02224N*m (Newton meters) of torque, but we don't want motor to run at 100%, so lets do this NewTorque = 0.02224N*m / 0.75 = 0.03N*m;

Thanks you have been helping me all way.since i cannot have a gearing system i will use rubberbands or anything stronger and see what happens.I think the gears are originally 6v but im pushing them at 9v.hence higher velocity.but hopefully i shall try to contain them.(please give any other ideas apart from gearing)Thanks

The easiest way to increase torque is to use a rubber band across the output shaft of the motor (small diameter) and then across a large wheel/cup/plate/disc on your actual wheel shaft. Maybe even directly around the wheels. Getting the rubber band to stay on and not jump off is tricky; you may need to build some rims with glue or epoxy or plastic or something.

I shall try that method as the wheels have to 7.5 cm or 8cm cd's i will see how to do it(if you have a tutorial just tell me.

Another cheap method to reduce RPM and increase torque:Mount the motor so that it shaft is parallel to the wheel's axle and the motor's shaft contact the outer edge of the wheel. The reduction ratio is the wheel's diameter divider by the motor's shaft diameter. The torque is increase by the inverse of the speed reduction ratio minus some frictional looses.The trickiest part is adjusting the motor shaft pressure on the wheel. Too little and the shaft slips, too much and the motor won't turn.

I've built a couple of robots using this method and they did run well. Best was that the cost was very low.

Another cheap method to reduce RPM and increase torque:Mount the motor so that it shaft is parallel to the wheel's axle and the motor's shaft contact the outer edge of the wheel. The reduction ratio is the wheel's diameter divider by the motor's shaft diameter. The torque is increase by the inverse of the speed reduction ratio minus some frictional looses.The trickiest part is adjusting the motor shaft pressure on the wheel. Too little and the shaft slips, too much and the motor won't turn.

I've built a couple of robots using this method and they did run well. Best was that the cost was very low.